Inadequacy of high K+/nigericin for calibrating BCECF. II. Intracellular pH dependence of the correction.

In the accompanying study [G. Boyarsky, C. Hanssen, and L.

Inadequacy of high K+/nigericin for calibrating BCECF. I. Estimating steady-state intracellular pH.

Intracellular pH (pHi) was measured in single vascular smooth muscle (VSM) cells, cultured from rabbit abdominal aorta, using 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF) on a microscope-based fluorescence system. Three lines of evidence are presented that using nigericin along with high external K+ to calibrate intracellular BCECF produces systematic errors in pHi. 1) The intrinsic buffering power (beta int), measured using weak bases (e.

Superiority of in vitro over in vivo calibrations of BCECF in vascular smooth muscle cells.

We measured intracellular pH (pHi) in single vascular smooth muscle cells (VSM) cultured from rabbit abdominal aorta, using 2',7'-biscarboxyethyl-5(6)carboxyfluorescein (BCECF) on a microscope-based fluorimetric system. We previously found substantial errors introduced by using high K+/nigericin to calibrate intracellular BCECF (1). We also previously demonstrated that the necessary correction (pHcor) to the high K+/nigericin-calibrated pHi was linearly dependent on pHi, increasing with increasing pHi (2).

The lupus anticoagulant. High incidence of 'negative' mixing studies in a human immunodeficiency virus-positive population.

We identified 100 patients (51 males and 49 females) as having the lupus anticoagulant. The following diagnoses were found in the patient population: human immunodeficiency virus positivity, 20%; systemic lupus erythematosus, 10%; prolonged preoperative activated partial thromboplastin time (APTT), 10%; procainamide hydrochloride-induced inhibitor, 9%; deep vein thrombosis, 6%; seizure disorders/epilepsy, 5%; and miscellaneous conditions, 40%. Identification was based on a prolonged APTT (> 40 seconds) that normalized with increased phospholipid concentrations and/or a prolonged Russell viper venom clotting time patient-control ratio of 1.